Solar power involves the conversion of sunlight into electrical energy. Traditionally, this has been accomplished using photovoltaics, concentrated photovoltaics, and concentrated solar thermal devices.
Photovoltaics convert light into electric current using photons from the sun to separate electrons and holes in semiconductor p-n junctions. Energy generation using photovoltaics has long been viewed as a sustainable technology which utilizes a plentiful renewable energy source (the sun). Conversion of sunlight to electricity occurs without emission or chemical byproducts.
Concentrated solar thermal systems use lenses/mirrors and tracking systems to focus sunlight. Concentrator systems convert the sun's radiation to heat which powers steam turbines to generate electricity. Many concentrating technologies exist, for example: parabolic trough, Fresnel reflector, Stirling dish, and solar tower.
While both photovoltaic and concentrator technologies are seeing large scale adoption, both have drawbacks limiting commercial viability. Most competitive photovoltaics must be fabricated from expensive highly-pure semiconductor components. Similarly, concentrator systems often use large/expensive tracking systems and precision machined mirrors and lenses.